docs: def normalize(self, mag=1.):
          """Normalize a Channel, set `null` to 0 and the mag to given value.
  
          Parameters
          ----------
          mag : float (optional)
              New value of mag. Default is 1.
          """
  
          def f(dataset, s, null, mag):
              dataset[s] -= null
              dataset[s] /= mag
  
          if self.signed:
              mag = self.mag() / mag
          else:
              mag = self.max() / mag
          self.chunkwise(f, null=self.null, mag=mag)
          self._null = 0